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aromatic acid or a mixture of the salts of an aromatic and
aliphatic acid. The reaction is precisely analogous to the
process used for the preparation of aliphatic ketones,

2C0HaCOOca' = CGHaCO.CeHa + CaCCX


C8HaCOOca' + CII3COOca' - C6ITS.CO.CH«  + CaCO,.


They possess the usual properties of ketones of the aliphatic
series (see p. 69), which are illustrated by the various reactions
described at the end of this preparation..

A special interest attaches to the oximes of those ketones
which contain two different radicals linked to the CO
group. Many of these substances exist in two isomeric
forms, which are readily converted into one another. Phenyl-
tolylketoxime exists in two forms and benzildioxime in three
forms, which cannot be explained by structural differences
of constitution. They must therefore represent different
space configurations of a type analogous to that of citra-
conic and mesaconic acid (Hantzsch, see p. 265). They
are distinguished by the terms " syn " and " anti," corresponding
to " cis " and " trans " among the unsaturated acids. " Anti "
signifies away from the group, the name of which follows ;
"syn" signifies the position near that group (see pp. 283 and


CflIIa.C.CcH4.CH3                  CcHa.C.CBH4.CII3

HO.N                                         N.OH

J5>«-Phenyltolylketoxime.                  A »#-Phenyltolylketoxime.

Benzil forms three dioximes which are distinguished Sy the
names " syn," "anti," and "amphi."

I I,C. C. C0HB     CaHs. C - C. CGH5   CCH5, C ---- C. CQH5
HO.N N.OH         HO.N   HO.N                    N.OH HO.N

anti.                           amphi.                                         syn.

The action of PCL-, on these substances, known as Beckmann's
reaction, is of great importance in distinguishing the different